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STAR GeneCounts for most genes are 0

Hello all, I am relatively new to this field.

I am doing an RNA-seq alignment and expecting a gene count output for a prokaryote genome. I have an annotation GTF file in which I have converted the third column into "exon" for the alignment to work. Everything seemed well but the readspergene.out.tab file has mostly 0 for the gene counts.example genecount output

Can anyone help diagnose what the problem is? Thank you

star rna-seq

What STAR commands did you run for generating the genome index and for aligning? Also, you may want to share both the STAR alignment log and a few lines from your modified GTF file.

It looks like most of the reads aligned outside your annotated “transcripts”. I would double-check that your annotations are in the same coordinate system as your genome.

a prokaryote genome ... I have converted the third column into "exon"

I guess the problem is somewhere here and agree that you should post an excerpt from your GTF file. Coming from a prokaryote that doesn't have splicing it is likely not in a proper format and lacks exon annotation (and changing only the type from CDS or whatever to exon doesn't cut it). In principle, you won't even need a splicing aligner here at all for that matter.

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